The ultimate goal of this SBIR is to identify genes that play a critical role in the development of prostate cancer. The specific aim of Phase I is to use differential display (Liang and Pardee, 1992) to identify differentially expressed genes in normal prostate and tumorigenic prostate cell lines. Differentially amplified bands will be evaluated by hybridization to Northern blots. Viable candidate genes will be sequenced and compared for homology to known genes in GenBank. In addition to identifying candidate genes for prostate cancer, modifications to increase the specificity and efficiency of the differential display technique will be tested. These will include the use of alternate primers and an assessment of the feasibility of incorporating a subtractive hybridization step. Since prostate cancer represents the most frequent cancer in US males, an understanding of the molecular nature of the disease will have significant medical impact.